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ALSA: usb-audio: detect implicit feedback on Roland devices

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All the Roland/Edirol/BOSS USB audio devices that need implicit feedback
show this unambiguously in their descriptors, so it might be a good idea
to let the driver detect this.

This should make playback work correctly (at least with Jack) with the
following devices:
- BOSS GT-100
- BOSS JS-8 Jam Station
- Edirol M-16DX
- Roland GAIA SH-01

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
This commit is contained in:
Clemens Ladisch 2013-02-03 22:31:20 +01:00
parent 8f898e92ae
commit ba7c2be114
1 changed files with 41 additions and 0 deletions
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41
sound/usb/pcm.c
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@ -298,6 +298,35 @@ static int deactivate_endpoints(struct snd_usb_substream *subs)
return 0;
}
static int search_roland_implicit_fb(struct usb_device *dev, int ifnum,
unsigned int altsetting,
struct usb_host_interface **alts,
unsigned int *ep)
{
struct usb_interface *iface;
struct usb_interface_descriptor *altsd;
struct usb_endpoint_descriptor *epd;
iface = usb_ifnum_to_if(dev, ifnum);
if (!iface || iface->num_altsetting < altsetting + 1)
return -ENOENT;
*alts = &iface->altsetting[altsetting];
altsd = get_iface_desc(*alts);
if (altsd->bAlternateSetting != altsetting ||
altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC ||
(altsd->bInterfaceSubClass != 2 &&
altsd->bInterfaceProtocol != 2 ) ||
altsd->bNumEndpoints < 1)
return -ENOENT;
epd = get_endpoint(*alts, 0);
if (!usb_endpoint_is_isoc_in(epd) ||
(epd->bmAttributes & USB_ENDPOINT_USAGE_MASK) !=
USB_ENDPOINT_USAGE_IMPLICIT_FB)
return -ENOENT;
*ep = epd->bEndpointAddress;
return 0;
}
/*
* find a matching format and set up the interface
*/
@ -393,6 +422,18 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
goto add_sync_ep;
}
}
if (is_playback &&
attr == USB_ENDPOINT_SYNC_ASYNC &&
altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
altsd->bInterfaceProtocol == 2 &&
altsd->bNumEndpoints == 1 &&
USB_ID_VENDOR(subs->stream->chip->usb_id) == 0x0582 /* Roland */ &&
search_roland_implicit_fb(dev, altsd->bInterfaceNumber + 1,
altsd->bAlternateSetting,
&alts, &ep) >= 0) {
implicit_fb = 1;
goto add_sync_ep;
}
if (((is_playback && attr == USB_ENDPOINT_SYNC_ASYNC) ||
(!is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE)) &&